In a Long Term Evolution (LTE) system, centralized control of a communication network is currently adopted, that is, both uplink and downlink data of a User Equipment (UE) need to be controlled by the network to be transmitted and received. At present, communication between one UE and another UE is forwarded and controlled by the network, and there is no direct communication link between the UE and the other UE. In this scheme, data transmission between the UE and the network can be referred simply to as Device to Network (D2N) transmission, as illustrated in FIG. 1.
In future development of a mobile communication system, in order to better satisfy the demand of a user and to improve the efficiency of exchanging information between devices, a mechanism of a Device to Device (D2D) discovery and even Device to Device (D2D) communication between the mobile devices has been introduced. In a D2D communication mode, some Device to Device (D2D) communication is allowed between one UE and another UE, and the direct communication link can be established under the control or assistance by the network, as illustrated in FIG. 2. D2D communication between the UE and the other UE is based upon a discovery of a UE nearby.
In the existing LTE system, a UE only supports D2N transmission, so the UE can only report information related to a D2N link to the network side so that the network side will make a correct decision according to the D2N link information reported by the UE. With the introduction of D2D, a UE supporting D2D transmission shall also support D2N transmission, and even the same UE may perform D2D transmission and D2N transmission at the same time. Since D2D transmission also needs to be controlled by the network, it shall be considered how to enable the network side to know D2D link information and to distinguish the D2D link information from the D2N link information, so that the network side can manage and schedule the D2D link and the D2N link. However there has been absent so far a solution to enabling the network side to know link information of a UE supporting D2D communication and to distinguish D2D link information from D2N link information.
In summary there has been absent so far a solution to enabling the network side to know link information of a UE supporting D2D communication and to distinguish D2D link information from D2N link information.